This blog provides updated forecasts and comments on current weather or other topics

Wednesday, April 7, 2010

Monday's "Surprise Storm"

Weather prediction has come a long way, but sometimes forecasters miss a significant event and Monday's windstorm over the Oregon coast and the Willamette Valley was a good example. The satellite picture above shows a tight low center making landfall near the Oregon/Washington border. As shown in the list below, winds of 50-70 mph were observed at a number of locations along the Oregon coast (click on the graphic to get an enlarged clear image)And here is a plot at Newport, Oregon, where there was a peak gust of roughly 55 knots on Monday, April 5th.The forecast from the National Weather Service distributed on Sunday was:

Clearly, the forecast models had some problems the day before--which is not surprising for a small scale low coming off the Pacific. Below is the wind and sea-level forecast valid 2 PM on Monday for a simulation started at 5 AM on Sunday. A weak 1003 mb low was evident as we brisk, but modest winds. Contrast that with the second graphic for a forecast started 24-h later--a 998 mb low and much stronger coastal winds.

This is not the first surprise storm associated with a small, intense low center to hit Oregon...another occurred during Feb 7, 2002---the South Valley Surprise Storm (check out: http://www.climate.washington.edu/stormking/ to find a description of that event).